Circuit Description

The Keyword protocol utilizes a single wire bi-directional data line between the modules and the scan tool. The message structure is a request and response arrangement. Keyword serial data is used for scan tool diagnostics only. The modules do not exchange data on this circuit.

The following modules are connected to the Keyword serial data circuit:

• Engine Control Module (ECM)
• Transmission Control Module (TCM) w/M82
• Headlamp Assembly-LF w/export
• Headlamp Assembly-RF w/export
  Fig 1: Scan Tool Does Not Communicate With Keyword Data Line - Diagnostic Table (Steps 1 - 3)

  Courtesy of GENERAL MOTORS CORP.
  Fig 2: Scan Tool Does Not Communicate With Keyword Data Line - Diagnostic Table (Steps 4 - 7)

  Courtesy of GENERAL MOTORS CORP.